Nonvolatile memory elements are used in systems in which persistent storage required. For example, digital cameras use nonvolatile memory cards to store images and digital music players use nonvolatile memory to store audio data. Nonvolatile memory is also used to persistently store data in computer environments. Nonvolatile memory is often formed using electrically-erasable programmable read only memory (EPROM) technology. This type of nonvolatile memory contains floating gate transistors that can be selectively programmed or erased by application of suitable voltages to their terminals.
As fabrication techniques improve, it is becoming possible to fabricate nonvolatile memory elements with increasingly smaller dimensions, and therefore low power consumption. However, as device dimensions shrink and as operating voltages decrease, data retention issues are posing challenges for nonvolatile memory technology.
Therefore, there is a need for a memory array that can meet the design criteria for advanced memory devices.